• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.709-714
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• 1997

Recently, the repair materials for defected RC structures are being developed and the performance on repaired RC structures are being studied. This experiment is aimed to evaluate the flexural performance of the RC beams repaired by premix-type materials. The parameters used in this study is the repair materials, the repair length and the treatment of interface. Flexural capacity of repaired RC beams except the polymer-repaired RC beams are similar to that of the control beam. In the flexural capacity, the RC beams treated with chipping show better results than the RC beam without chipping. The various repair lengths of the repaired RC beam are not affected to the flexural capacity.

• 한국해안·해양공학회논문집
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• 제21권2호
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• pp.191-195
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• 2009

손상된 철근콘크리트 보를 모의하기 위해 사전균열을 발생시킨 후, GFRP Bar와 GSP 매입공법으로 보수하여 피로실험을 수행하였다. 피로실험 결과, 실험보는 피로하중 초기 싸이클에서 대부분의 잔류처짐과 균열이 발생하고 싸이클 수에 따른 이들의 증가율은 미미하였다. 보수보의 정적강도는 보수하지 않은 보에 비해 크게 증가하였지만, 피로강도는 감소하였다. S-N 곡선에서, GFRP Bar 보수보의 피로강도는 정적강도의 58%, GSP 보수보의 피로강도는 52%였다.

• Advances in concrete construction
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• 제8권2호
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• pp.91-100
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• 2019

In this paper three damaged exterior RC beam-column joints made of recycled aggregate concrete (RAC) were repaired. The aim of the study was to restore back the lost capacity of the beam-column joint to the original state or more. A relatively cheap material locally available galvanized steel welded wire mesh (GSWWM) of grid size 25 mm was used to confine the damaged region and then jacketed with cement mortar. Repaired specimens were also subjected to similar cyclic displacement as those of unrepaired specimens. Seismic parameters such as load carrying capacity, ductility, energy dissipation, stiffness degradation etc. were analyzed. Results show that repaired specimens exhibited better seismic performance and hence the adopted repairing strategies could be considered as satisfactory. These findings would be helpful to the field engineers to adopt a suitable rapid and cost efficient repairing technique for restoring the damaged frame structural joints for post earthquake usage.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.138-145
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• 2001

This paper presents F.E.M. analysis result about the behavior of R.C. beam repaired with steel plate and fiber sheet. The effect of repairing varies with reinforcement ratio of R.C. beam, plate thickness, numbers of fiber sheet, and repairing length, etc. F.E.M. analysis using a program, DIANA, was carried out taking these factors as parameter in this study. Analysis result shows that repaired R.C. beam behaves differently according to parameters and certain cases imply that repairing is useless or may lay structure in dangerous condition. F.E.M. model considers that interfacial behavior between different two parts of repaired beam is rigid based on an assumption that adhesive failure does not appear before yielding of reinforcement and its analysis shows the result coincides with that of experiment.

• 산업기술연구
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• 제26권B호
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• pp.101-110
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• 2006

The purpose of this study was to investigate the flexural, interfacial behavior, crack propagation, nonlinear behavior, effect repaired and rehabilitated with VES-LMC using RC beam with 4-point-loading test. The results were following: The test result showed that repair and rehabilitation effect increased as its depth increased, which was verified by the increase of flexural stiffness. More than 40% of stiffness was improved when the depth of repair was up to steel position. However, there was a little difference between 8cm and 12cm repaired beam. This means the repair depth must be considered. The interfacial behavior data showed that the repaired or rehabilitated beams had a little relative displacement. This means that two materials behave comparatively acting together. This suggested that interface treatment were one of the most important jobs in composite beams.

• Earthquakes and Structures
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• 제26권1호
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• pp.49-58
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• 2024

The purpose of this study was to develop a system capable of restoring the seismic performance of a precast concrete (PC) connection damaged by an earthquake. The developed PC connection consists of a top-and-seat angle, post-tensioning (PT) tendons, and U-shaped steel. The PC beam can be replaced by cutting the PT tendons in the event of damage. In addition, the seismic performance of the developed PC beam-column connection was evaluated experimentally. A PC beam-column connection specimen was fabricated, and a quasistatic cyclic loading test was conducted to a maximum drift ratio of 2.3%. Subsequently, the PC beam was replaced by a new PC beam, and the repaired PC connection was loaded to a maximum drift ratio of 5.1%. The structural performance of the repaired PC connection was then compared with that of the original PC connection. The difference in the load at the drift ratio of 2.3% between the original and the repaired PC specimens was only 0.2%. The residual drift ratio in the repaired PC specimen did not exceed 1.0% at the 2.0 % drift ratio cycles, which satisfies the life safety performance level specified in ACI 374.2R-13. When the developed PC connection system is used, structural performance can be restored by rapidly replacing the damaged elements.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.543-548
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• 2003

In this study, a numerical model is developed using axial deformation link elements that can effectively predict the failure behavior of RC type structures. Using this mod 1, numerical analysis was performed to investigate the strengthening effect and failure behavior of structures repaired with a new material. High-Performance Cementitious Composites, which is characterized by its ductility with 5% strain-capacity is used as a repair material. To investigate the validity of developed numerical model, simulations of direct tension specimen and flexural specimen are performed and the results are compared with published ones. The similar analysis is performed for RC beam. Through this study, it is seen that predicted response has a good agreement with the experimental results. Using this verified numerical model, the strengthening effect of repaired with HPCC structure is analyzed through load-displacement curve and failure modes. Also, the same numerical analysis is performed in RC beam repaired with HPCC. The effect of HPCC ductility is estimated for the overall behavior of structures. Based on the results, the fundamental data are suggested for repaired structures with HPCC.

• Steel and Composite Structures
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• 제29권2호
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• pp.187-200
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• 2018

This paper handles the repairing of deficient square Concrete-Filled Steel-Tube (CFST) beams subject to bending through an experimental and numerical program. Eight square-CFST beams were tested. A 5-mm artificial notch was induced at mid-span of seven beams, four of them were repaired by using CFRP sheets and two were repaired by using GFRP sheets. The beam deflection, strain and ultimate moments were recorded. It was found that providing different cut-off points for the different layers of FRP sheets prohibited failure at termination points due to stress concentrations. Using different lengths of FRP sheets around the notch retarded crack propagation and prevented FRP rupture at the crack position. Finite element analysis was then conducted and the proposed FE model was verified against the recorded experimental data. The influence of various parameters as FRP sheet length, tensile modulus and the number of layers were studied. The moment capacity of damaged square-CFST beams was improved up to 77.6% when repaired by using four layers of CFRP, however, this caused a dramatic decrease in beam deflection. U-wrapping of notched-CFST beam with 0.75 of its length provided a comparable behaviour as wrapping the full length of the beam.

• Computers and Concrete
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• 제27권5호
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• pp.395-406
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• 2021

This study experimentally and analytically investigates the shear behavior of corroded reinforced concrete (RC) beams repaired using steel fiber-reinforced concrete (SFRC) in the flexural zone. The experimental parameters are the corrosion degree (0%, 12%, and 17%) and the steel fiber volume in the SFRC (1.0%, 1.5%, and 2.0%). The test results reveal that corrosion degree significantly affects the shear resistance of the beams. The shear capacity of the beam with the corrosion degree of 17% was higher than that of the uncorroded beam, whereas the shear capacity of the beam with the corrosion degree of 12% was lower than that of the uncorroded beam. The shear efficiency of damaged beams can be recovered by repairing them using SFRC that contains a reasonable amount of steel fibers. In addition, two methods to estimate the shear capacity of the repaired beams are developed using the modified truss analogy and strut-and-tie models. The estimated shear capacity of the beam using the modified truss analogy model agrees well with the experimental data.

• Smart Structures and Systems
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• 제7권5호
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• pp.329-348
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• 2011

Large-scale earthquakes pose serious threats to infrastructure causing substantial damage and large residual deformations. Superelastic (SE) Shape-Memory-Alloys (SMAs) are unique alloys with the ability to undergo large deformations, but can recover its original shape upon stress removal. The purpose of this research is to exploit this characteristic of SMAs such that concrete Beam-Column Joints (BCJs) reinforced with SMA bars at the plastic hinge region experience reduced residual deformation at the end of earthquakes. Another objective is to evaluate the seismic performance of SMA Reinforced Concrete BCJs repaired with flowable Structural-Repair-Concrete (SRC). A $\frac{3}{4}$-scale BCJ reinforced with SMA rebars in the plastic-hinge zone was tested under reversed cyclic loading, and subsequently repaired and retested. The joint was selected from an RC building located in the seismic region of western Canada. It was designed and detailed according to the NBCC 2005 and CSA A23.3-04 recommendations. The behaviour under reversed cyclic loading of the original and repaired joints, their load-storey drift, and energy dissipation ability were compared. The results demonstrate that SMA-RC BCJs are able to recover nearly all of their post-yield deformation, requiring a minimum amount of repair, even after a large earthquake, proving to be smart structural elements. It was also shown that the use of SRC to repair damaged BCJs can restore its full capacity.